python3: upgrade to 3.7.2

I took the same approach as the recent perl upgrade: write recipe from scratch,
taking the pieces from the old recipe only when they were proven to be necessary.

The pgo, manifest and ptest features are all preserved.

New features:

- native and target recipes are now unified into one recipe

- check_build_completeness.py runs right after do_compile() and verifies that
all optional modules have been built (a notorious source of regressions)

- a new approach to sysconfig.py and distutils/sysconfig.py returning values
appropriate for native or target builds: we copy the configuration file to a
separate folder, add that folder to sys.path (through environment variable
that differs between native and target builds), and point python to the file
through another environment variable.

There were a few other patches where it was difficult to decide if the patch
is still relevant, and how to test that it works correctly; please add those
as-needed by testing the new python.

(From OE-Core rev: 02714c105426b0d687620913c1a7401b386428b6)

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3/cgi_py.patch

@@ -1,11 +1,20 @@
-Lib/cgi.py: Update the script as mentioned in the comment
+From 62336285cba38017b35cb761c03f0c7e80a671a3 Mon Sep 17 00:00:00 2001
+From: Mark Hatle <mark.hatle@windriver.com>
+Date: Wed, 21 Sep 2011 20:55:33 -0500
+Subject: [PATCH] Lib/cgi.py: Update the script as mentioned in the comment
 
 Upstream-Status: Inappropriate [distribution]
 
 Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
 
---- Python-2.6.6/Lib/cgi.py.orig	2010-08-01 22:14:27.000000000 -0500
-+++ Python-2.6.6/Lib/cgi.py	2011-09-21 15:28:40.478208631 -0500
+---
+ Lib/cgi.py | 11 +----------
+ 1 file changed, 1 insertion(+), 10 deletions(-)
+
+diff --git a/Lib/cgi.py b/Lib/cgi.py
+index 8cf6687..094c7b4 100755
+--- a/Lib/cgi.py
++++ b/Lib/cgi.py
 @@ -1,13 +1,4 @@
 -#! /usr/local/bin/python
 -